Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

202
FXUS63 KLOT 082335
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
635 PM CDT Wed Apr 8 2026

.KEY MESSAGES...

- Gusty south-southwest winds to 35-40 mph will persist through
  this evening.

- Mild conditions with periods of showers and some storms
  through Friday, then again from late weekend into early next
  week.

- Combined rainfall amounts tonight through Friday may exceed
  an inch across portions of the forecast area. This could
  produce new rises on area rivers and creeks.

&&

.DISCUSSION...
Issued at 239 PM CDT Wed Apr 8 2026

A stacked low pressure system continues to drift across the
Canadian- ND border and will be moving into the northern Great
Lakes tonight. Stretching from this low across southern MN,
northwest IA, and eastern NE is a cold front that will be moving
into northern IL (and eventually northwest IN) late this
evening and overnight. Current regional radar does show some
spotty echoes along and just ahead of the cold front in IA and
MN but precipitation does not appear to be reaching the ground
presently. However, as the front continues to approach the
coverage of rain showers should increase with the potential for
a few embedded thunderstorms to develop as well. Given that
instability profiles continue to look rather modest have opted
to keep a low (10-15%) chance for thunder in the forecast, but
suspect many will just see showers tonight. That said, as the
front progresses across our area the coverage of showers (and
any storms) should diminish as the front encounters drier air
with southward extent. Thus, there is a good chance that those
south of the Kankakee River Valley could remain rain-free
tonight. Regardless, mild temperatures in the low to mid-50s are
expected tonight with some occasional southwesterly wind gusts
around 20-25 mph.

Heading into Thursday, the front will begin to stall near (or
just south of) the I-80 corridor. Due to the more limited
moisture and weaker forcing atop the front, dry conditions are
expected for Thursday morning. Though, another shortwave impulse
will be ejecting out of the central Plains Thursday afternoon
which should be able to regenerate at least some isolated to
widely scattered showers and thunderstorms along and just south
of the stalled frontal boundary. While forecast soundings do
show around 30-35 kts of bulk shear to be present Thursday
afternoon, the modest instability (around 300- 500 J/kg) looks
to limit storm organization and keep the threat for any severe
weather low. Otherwise, expect another warm afternoon with highs
once again in the mid to upper 60s. Though some locations south
of the front could get into the lower 70s if skies clear
enough.

In addition to the aforementioned shortwave impulse Thursday
afternoon, a broader shortwave trough is expected to be diving
out of the northern Plains Thursday night. This trough should
provide much better forcing and allow for a broader coverage of
showers and embedded thunderstorms to develop across northern IL
and northwest IN through the night. Since the frontal boundary
will be very slow moving during this time and storm motions are
forecast to be nearly parallel to the boundary, conditions
continue to look favorable for training showers and
thunderstorms. As a result guidance is in good agreement that a
swath of 0.5-1.0 inch rain amounts will materialize over
portions of northern IL and/or northwest IN Thursday night with
a 20-30% chance for localized amounts in excess of an inch.
While the exact location of these heaviest rain amounts is still
uncertainty due to the convective nature, the already saturated
ground and elevated rivers won`t take much to get flooding
issues to develop. Therefore, we will be watching trends closely
and may need to consider a Flood Watch if confidence on the 1+
inch amounts grows. In the meantime make sure you keep checking
back for forecast updates and ensure you have ways to receive
flood alerts should they be issued especially if you live near
area rivers.

The front is expected to begin to slowly move into the Ohio
River Valley on Friday which should allow for rain to taper from
northwest to southeast by Friday evening. In the wake of the
front, more seasonable temperatures can be expected with highs
in the mid to upper 50s Friday afternoon inland with highs in
the 40s near the lake. Mid-level ridging will move into the
Great Lakes Friday nigh and persist through at least Saturday
evening keeping dry conditions in play for the first part of the
weekend. However, the persistent east-northeast winds don`t
look to allow temperatures to improve much Saturday with highs
once again forecast to be in the mid-50s to lower 60s inland
with 40s expected near the lake.

While we enjoy a break in the active weather, upper-level
troughing (comprised of several shortwaves) is forecast to
develop across the western CONUS this weekend. By Saturday night
one of these shortwaves is projected to break off the main
trough and traverse from the central Plains into the upper
Mississippi Valley. Guidance continues to indicate that as this
shortwave nears the Mississippi river a plume of showers and
thunderstorms should develop ahead of it and ride the western
periphery of the aforementioned ridge. This trajectory favors
most of the showers/storms to occur in IA and southern WI, but
give the close proximity to us cannot completely rule out a few
shower/storms brushing the northwest portion IL. At this time
have opted not to change the 20-40% POPs offered by WPC and the
NBM but suspect these are a bit broad and may need to get
trimmed if trends continue.

Regardless of what happens Saturday night, the ridge should
begin to get pushed east by yet another shortwave that is
forecast to eject across the central Plains on Sunday. This next
shortwave will also lead to the development of additional
showers and thunderstorms on which could arrive in our area as
early as Sunday afternoon/evening. However, timing on when
exactly this next round of rain arrives continues to be very
uncertain in latest ensemble guidance and thus confidence is
low. That said, it does look that a stormy period of weather
will be in play for us during the Sunday through Tuesday
timeframe so be sure to stay tuned.

Yack

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 635 PM CDT Wed Apr 8 2026

Forecast concerns include...

Strong/gusty south/southwest winds this evening.
Chance of showers early Thursday morning.
Wind shift to northeast late Thursday afternoon.
Scattered showers Thursday evening with possible mvfr cigs/vis.

South/southwest winds gusting into the 30-35 kt range will
continue through sunset and then only slightly diminish into the
25-30 kt range. Speeds and gusts will steadily diminish
overnight with directions turning southwest and then westerly as
a cold front moves across the area. Westerly winds are expected
Thursday and then winds will shift northerly and likely to the
northeast for ORD/MDW/GYY by late afternoon or early Thursday
evening. Only medium confidence for wind directions and timing
and changes are possible with later forecasts.

There will be a chance of showers ahead of the cold front
overnight toward daybreak. These showers will likely be in a
weakening phase as they move across northern IL but some brief,
limited 5-6sm vis reduction is possible.

A better chance of prevailing rain is expected Thursday evening
into early Friday morning with some differences in start times,
which could be late afternoon across northwest IL and at RFD.
Later forecasts will likely need a period of prevailing rain.
Prevailing mvfr cigs/vis are expected and ifr cigs/vis will be
possible by early Friday morning. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 4 AM CDT Thursday for the IL
     nearshore waters.

     Small Craft Advisory until 7 AM CDT Thursday for the IN
     nearshore waters.

&&

$$

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